Internet DRAFT - draft-ketant-lsr-ospf-l2bundles
draft-ketant-lsr-ospf-l2bundles
Link State Routing K. Talaulikar
Internet-Draft P. Psenak
Intended status: Standards Track Cisco Systems
Expires: January 1, 2021 June 30, 2020
Advertising L2 Bundle Member Link Attributes in OSPF
draft-ketant-lsr-ospf-l2bundles-02
Abstract
There are deployments where the Layer 3 interface on which OSPF
operates is a Layer 2 interface bundle. Existing OSPF advertisements
only support advertising link attributes of the Layer 3 interface.
If entities external to OSPF wish to control traffic flows on the
individual physical links which comprise the Layer 2 interface bundle
link attribute information about the bundle members is required.
This document introduces the ability for OSPF to advertise the link
attributes of layer 2 (L2) Bundle members.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 1, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. L2 Bundle Member Attributes . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . 7
6.2. Informational References . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
There are deployments where the Layer 3 interface on which an OSPF
adjacency is established is a Layer 2 interface bundle, for instance
a Link Aggregation Group (LAG) [IEEE802.1AX] . This reduces the
number of adjacencies which need to be maintained by the routing
protocol in cases where there are parallel links between the
neighbors. Entities external to OSPF such as Path Computation
Elements (PCE) [RFC4655] may wish to control traffic flows on
individual members of the underlying Layer 2 bundle. In order to do
so link attribute information about individual bundle members is
required. The protocol extensions defined in this document provide
the means to advertise this information.
This document introduces new sub-TLVs to advertise link attribute
information for each of the L2 Bundle members which comprise the
Layer 3 interface on which OSPF operates. Similar capabilities were
introduced in IS-IS via [RFC8668].
[RFC8665] and [RFC8666] introduced the adjacency segment identifier
(Adj-SID) link attribute for OSPFv2 and OSPFv3 respectively which can
be used as an instruction to forwarding to send traffic over a
specific link [RFC8402]. This document enables the advertisement of
the Adj-SIDs using the same Adjacency SID sub-TLV at the granularity
level of each L2 Bundle member link so that traffic may be steered
over that specific member link.
Note that the new advertisements at the L2 Bundle member link level
in this document are intended to be provided to external (to OSPF)
entities and does not alter or change OSPF route computation process.
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The following items are intentionally not defined and/or are outside
the scope of this document:
o What link attributes will be advertised. This is determined by
the needs of the external entities.
o A minimum or default set of link attributes.
o How these attributes are configured
o How the advertisements are used
o What impact the use of these advertisements may have on traffic
flow in the network
o How the advertisements are passed to external entities
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. L2 Bundle Member Attributes
A new L2 Bundle Member Attributes sub-TLV is introduced to advertise
L2 Bundle member attributes in both OSPFv2 and OSPFv3. In case of
OSPFv2, this sub-TLV is an optional sub-TLV of the OSPFv2 Extended
Link TLV that is used to describe link attributes via the OSPFv2
Extended Link Opaque LSA [RFC7684]. In case of OSPFv3, this sub-TLV
is an optional sub-TLV of the Router Link TLV of the OSPFv3 E-Router-
LSA [RFC8362].
When the OSPF adjacency is associated with L2 Bundle interface, this
sub-TLV is used to advertise the underlying L2 Bundle member links
along with their individual link attributes. Inclusion of this
information implies that the identified link is a member of the L2
bundle associated with OSPF L3 link and that the member link is
operationally up. Therefore advertisements of member links MUST NOT
be done when the member link becomes operationally down or it is no
longer a member of the identified L2 Bundle.
The L2 Bundle Member Attributes sub-TLV has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L2 Bundle Member Descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Member Link attribute sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: L2 Bundle Member Attributes sub-TLV Format
Where:
Type: TBD1 for OSPFv2 and TBD2 for OSPFv3
Length: Variable.
L2 Bundle Member Descriptor: A 4 octet Link Local Identifier as
described in [RFC4202] and used in [RFC8510] for the member link.
Link attributes for L2 Bundle Member Links are advertised as sub-TLVs
of the L2 Bundle Member Attribute sub-TLV.
In the case of OSPFv2, the L2 Bundle Member Attributes sub-TLV shares
the sub-TLV space of the Extended Link TLV and the sub-TLVs of the
Extended Link TLV MAY be used to describe the attributes of the
member link. The Figure 2 below lists sub-TLVs and their
applicability for L2 Bundle member links. The sub-TLVs that are not
applicable MUST NOT be used as sub-TLVs for the L2 Bundle Member
Attributes sub-TLV. Specifications that introduce new sub-TLVs of
the Extended Link TLV MUST indicate their applicability for the L2
Bundle Member Attributes sub-TLV. An implementation MUST ignore any
sub-TLVs received that are not applicable in the context of the L2
Bundle Member Attribute sub-TLV.
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Y - applicable
N - not-applicable
1 SID/Label (N)
2 Adj-SID (Y)
3 LAN Adj-SID/Label (Y)
4 Network-to-Router Metric (N)
5 RTM Capability (N)
6 OSPFv2 Link MSD (N)
7 Graceful-Link-Shutdown (N)
8 Remote IPv4 Address (N)
9 Local/Remote Interface ID (N)
10 Application Specific Link Attributes (Y)
11 Shared Risk Link Group (Y)
12 Unidirectional Link Delay (Y)
13 Min/Max Unidirectional Link Delay (Y)
14 Unidirectional Delay Variation (Y)
15 Unidirectional Link Loss (Y)
16 Unidirectional Residual Bandwidth (Y)
17 Unidirectional Available Bandwidth (Y)
18 Unidirectional Utilized Bandwidth (Y)
19 Administrative Group (Y)
20 Extended Administrative Group (Y)
21 Maximum Link Bandwidth (Y)
22 Traffic Engineering Metric (Y)
TBD1 L2 Bundle Member Attributes (N)
Figure 2: Applicability of OSPFv2 Link Attribute sub-TLVs for L2
Bundle Members
In the case of OSPFv3, the L2 Bundle Member Attributes sub-TLV shares
the sub-TLV space of the Router Link TLV and the sub-TLVs of the
Router Link TLV MAY be used to describe the attributes of the member
link. The Figure 3 below lists sub-TLVs that are applicable for
Router Link TLV and their applicability for L2 Bundle member links.
The sub-TLVs that are not applicable MUST NOT be used as sub-TLVs for
the L2 Bundle Member Attributes sub-TLV. Specifications that
introduce new sub-TLVs of the Router Link TLV MUST indicate their
applicability for the L2 Bundle Member Attributes sub-TLV. An
implementation MUST ignore any sub-TLVs received that are not
applicable in the context of the L2 Bundle Member Attribute sub-TLV.
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Y - applicable
N - not-applicable
5 Adj-SID (Y)
6 LAN Adj-SID (Y)
7 SID/Label (N)
8 Graceful-Link-Shutdown (N)
9 OSPFv3 Link MSD (N)
10 Application Specific Link Attributes (Y)
11 Shared Risk Link Group (Y)
12 Unidirectional Link Delay (Y)
13 Min/Max Unidirectional Link Delay (Y)
14 Unidirectional Delay Variation (Y)
15 Unidirectional Link Loss (Y)
16 Unidirectional Residual Bandwidth (Y)
17 Unidirectional Available Bandwidth (Y)
18 Unidirectional Utilized Bandwidth (Y)
19 Administrative Group (Y)
20 Extended Administrative Group (Y)
21 Traffic Engineering Metric (Y)
22 Maximum Link Bandwidth (Y)
23 Local Interface IPv6 Address (N)
24 Remote Interface IPv6 Address (N)
TBD2 L2 Bundle Member Attributes (N)
Figure 3: Applicability of OSPFv3 Link Attribute sub-TLVs for L2
Bundle Members
3. IANA Considerations
This document adds new sub-TLVs to the OSPFv2 and OSPFv3 registry.
The following sub-TLV is added to the OSPFv2 Extended Link TLV sub-
TLVs registry under the OSPFv2 Parameters IANA registry:
Value: TBD1
Name: L2 Bundle Member Attributes
The following sub-TLV is added to the OSPFv3 Extended LSA sub-TLVs
registry under the OSPFv3 Parameters IANA registry:
Value: TBD2
Name: L2 Bundle Member Attributes
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4. Security Considerations
The OSPF protocol has supported the advertisement of link attribute
information, including link identifiers, for many years. The
advertisements defined in this document are identical to existing
advertisements defined in [RFC3630], [RFC4203], [RFC5329], [RFC7471],
[RFC8665] and [RFC8666] - but are associated with L2 links which are
part of a bundle interface on which the OSPF protocol operates.
There are therefore no new security issues introduced by the
extensions in this document.
As always, if the protocol is used in an environment where
unauthorized access to the physical links on which OSPF packets are
sent occurs then attacks are possible. The use of authentication as
defined in [RFC5709], [RFC7474], [RFC4552] and [RFC7166] is
recommended to prevent such attacks.
5. Acknowledgements
This document leverages the similar work done for IS-IS and the
authors of this document would like to acknowledge the contributrions
of the authors of [RFC8668].
6. References
6.1. Normative References
[IEEE802.1AX]
Institute of Electrical and Electronics Engineers, "IEEE
Standard for Local and Metropolitan Area Networks - Link
Aggregation.", Nov 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
<https://www.rfc-editor.org/info/rfc4202>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
December 2019, <https://www.rfc-editor.org/info/rfc8666>.
6.2. Informational References
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<https://www.rfc-editor.org/info/rfc4203>.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, DOI 10.17487/RFC5329, September 2008,
<https://www.rfc-editor.org/info/rfc5329>.
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[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <https://www.rfc-editor.org/info/rfc5709>.
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166,
DOI 10.17487/RFC7166, March 2014,
<https://www.rfc-editor.org/info/rfc7166>.
[RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
<https://www.rfc-editor.org/info/rfc7471>.
[RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed.,
"Security Extension for OSPFv2 When Using Manual Key
Management", RFC 7474, DOI 10.17487/RFC7474, April 2015,
<https://www.rfc-editor.org/info/rfc7474>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8510] Psenak, P., Ed., Talaulikar, K., Henderickx, W., and P.
Pillay-Esnault, "OSPF Link-Local Signaling (LLS)
Extensions for Local Interface ID Advertisement",
RFC 8510, DOI 10.17487/RFC8510, January 2019,
<https://www.rfc-editor.org/info/rfc8510>.
[RFC8668] Ginsberg, L., Ed., Bashandy, A., Filsfils, C., Nanduri,
M., and E. Aries, "Advertising Layer 2 Bundle Member Link
Attributes in IS-IS", RFC 8668, DOI 10.17487/RFC8668,
December 2019, <https://www.rfc-editor.org/info/rfc8668>.
Authors' Addresses
Ketan Talaulikar
Cisco Systems
India
Email: ketant@cisco.com
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Peter Psenak
Cisco Systems
Apollo Business Center
Mlynske nivy 43
Bratislava 821 09
Slovakia
Email: ppsenak@cisco.com
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